Vascular filter device

ABSTRACT

A vascular filter device ( 1 ) comprises a plurality of filter elements ( 6 ) which are movable from a capturing position to an open position upon elapse of a predetermined period of time. In the capturing position the filter elements ( 6 ) are configured to capture thrombus passing through the inferior vena cava. In the open position the filter elements ( 6 ) are configured to facilitate unrestricted blood flow. The filter elements ( 6 ) are biased towards the open position. The filter ( 1 ) comprises a holder member ( 10 ) to temporarily hold the filter elements ( 6 ) in the capturing position until elapse of the predetermined period of time. The holder member ( 10 ) comprises a biostable wire element ( 12 ) which extends through an opening ( 13 ) in each filter element ( 6 ), and a biodegradable/bioabsorbable stop element ( 11 ). Upon biodegrading/bioabsorbing of the stop element ( 11 ), the filter elements ( 6 ) are free to move from the capturing position to the open position.

RELATED APPLICATIONS

This application claims the benefit of priority from U.S. ProvisionalApplication No. 61/145,303 filed on Jan. 16, 2009, the entire contentsof which are incorporated herein by reference.

INTRODUCTION

This invention relates to a vascular filter device and to a method ofmanufacturing such a device.

WO2008/010197 (Novate Medical Limited) describes such a device. Itcomprises a support extending around the vessel wall and which supportsa filter. The filter comprises a number of filter elements, and in someembodiments they are retained by a holder member in a closed state forcapturing thrombus. The holder member biodegrades after a period of timeand releases the filter elements so that they can move to an openposition against the vessel wall. The latter may be referred to asfilter conversion.

The invention is directed towards providing a filter device withadditional control over the conversion time and reliability.

SUMMARY OF THE INVENTION

According to the invention, there is provided a vascular filter devicecomprising a filter comprising one or more filter elements, the one ormore filter elements being movable from a capturing position to capturethrombus passing through a blood vessel, to an open position tofacilitate unrestricted blood flow. A holder holds the filter elementsin the capturing position. The filter elements may be biased towards theopen position, and the holder may be configured to temporarily hold thefilter element in the capturing position until elapse of a predeterminedperiod of time.

In one embodiment, the predetermined period of time is betweenapproximately 4 months and approximately 24 months.

In one embodiment, the predetermined period of time is betweenapproximately 4 days and approximately 4 months.

In one embodiment, at least part of the holder is biodegradable and/orbioabsorbable. In one embodiment, all of the holder is biodegradableand/or bioabsorbable. In one embodiment, at least part of the holder isbiostable.

In one embodiment, the holder comprises one or more predeterminedfailure points.

In one embodiment, at least part of the holder engages with the filterelement to hold the filter element in the capturing position.

In one embodiment, at least part of the holder extends through anopening in the filter element to hold the filter element in thecapturing position.

In one embodiment, the filter comprises a plurality of filter elements,and in the capturing position the filter elements are arranged with theopenings circumferentially spaced apart. In one embodiment, in thecapturing position the opening faces circumferentially. In oneembodiment, in the capturing position the holder comprises a firstelement extending through the opening and a second element to maintainthe first element extending through the opening. In one embodiment, inthe capturing position the second element connects a first end of thefirst element to a second end of the first element. In one embodiment,the first element is biostable. In one embodiment, the second element isbiodegradable and/or bioabsorbable. In one embodiment, the radialdimension of the filter element radially inwardly of the opening isgreater than the radial dimension of the filter element radiallyoutwardly of the opening. In one embodiment, at least part of theopening has a chamfered or rounded edge. In one embodiment, the holdercomprises a first element connected to a second element at a connectionpoint, the first element extending from the connection point through anopening in a first filter element, and the second element extending fromthe connection point through an opening in a second filter element.

In one embodiment, the element extends substantially radially from theconnection point through the opening in the filter element. In oneembodiment, the filter comprises a plurality of filter elements, and inthe capturing position the filter elements are arranged with theopenings aligned in a straight line. In one embodiment, in the capturingposition the openings are aligned longitudinally in a straight line. Inone embodiment, in the capturing position the openings are alignedradially in a straight line. In one embodiment, the longitudinal axis ofthe holder is substantially straight. In one embodiment, in a first endof the holder is disconnected from a second end of the holder. In oneembodiment, at least part of the holder is formed integrally with thefilter elements.

In one embodiment, the holder engages with the internal wall of theopening. In one embodiment, the holder engages with the filter elementexternally of the opening. In one embodiment, the holder issubstantially rigid. In one embodiment, the holder comprises at leastone pin element. In one embodiment, the pin element comprises a centralelement extendable through the opening in the filter element, and atleast one stop element at an end of the central element externally ofthe opening. In one embodiment, the pin element comprises a first stopelement at a first end of the central element and a second stop elementat a second end of the central element. In one embodiment, the stopelement is formed separately to the central element.

In one embodiment, at least one stop element is formed integrally withthe central element. In one embodiment, at least part of the stopelement is biodegradable and/or bioabsorbable. In one embodiment, atleast part of the stop element is biostable. In one embodiment, at leastpart of the central element is biostable. In one embodiment, at leastpart of the central element is biodegradable and/or bioabsorbable.

In one embodiment, the holding means extends around at least part of thefilter element to hold the filter element in the capturing position.

In one embodiment, the holder comprises a ring element. In oneembodiment, the holder comprises a tube element. In one embodiment, atleast part of the holder is substantially conically shaped. In oneembodiment, at least part of the holder comprises a mesh. In oneembodiment, the holder is located proximally of the distal end of thefilter element.

In one embodiment, the holder comprises a first opening through which afirst set of one or more filter elements extends in the capturingposition, and a second opening through which a second set of one or morefilter elements extends in the capturing position. In one embodiment,the first set of one or more filter elements extends through the firstopening in the open position.

In one embodiment, the wall thickness of the holder around the firstopening is greater than the wall thickness of the holder around thesecond opening. In one embodiment, the device is configured to couplethe holder to the filter element in the capturing position. In oneembodiment, the device is configured to couple the holder to the filterelement in the open position. In one embodiment, the filter elementcomprises at least one bend to couple the holder to the filter element.In one embodiment, the angle of the bend is greater than 60°.

In one embodiment, at least part of the filter element is twisted. Inone embodiment, the device comprises a vena cava filter.

In one embodiment, the holder comprises a ring around the filter elementends and an insert to retain the filter element ends in set positions.

In one embodiment, the holder comprises a pin extending through filterelement openings, and the pin is tied at its ends.

In one embodiment, the holder comprises a pin extending through filterelement openings and there is a heat-shrunk sleeve at the ends of thepin.

In one embodiment, the holder comprises a pin extending through filterelement openings and the pin has a clawed end with splayed-out claws forretention of the pin in place.

In one embodiment, the holder comprises a pin extending through filterelement openings and having barbed ends. In one embodiment, the pin isbent at the ends.

In one embodiment, the holder comprises a coupler through which filterelement ends extend. In one embodiment, the holder comprises screw capand the ends of the filter elements are engaged with threads of thescrew cap.

In one embodiment, the holder comprises coupler having an opening intowhich the ends of the filter elements are snap-fitted.

In one embodiment, the ends of the filter elements are hooked.

In one embodiment, the holder comprises a lumen for flow of biodegradedmaterial.

In one embodiment, the invention provides a method of manufacturing afilter device, the method comprising the step of engaging a holder withone or more filter elements to hold the one or more filter elements in acapturing position.

In one embodiment, the method comprises the step of extending at leastpart of the holder through an opening in the filter element.

In one embodiment, the method comprises the step of connecting a firstend of the holder to a second end of the holder to maintain the holderextending through the opening in the filter element. In one embodiment,the holder comprises a central element extendable through the opening inthe filter element, and at least one stop element at an end of thecentral element externally of the opening. In one embodiment, thecentral element and the stop element are formed integrally. In oneembodiment, the method comprises the step of deforming the holder toform the central element and the stop element. In one embodiment, thecentral element and the stop element are formed separately. In oneembodiment, the method comprises the step of attaching the stop elementto the central element. In one embodiment, the method comprises the stepof extending the holder around at least part of the filter element. Inone embodiment, the holder is chosen with a configuration according todesired degradation time as a function of time for flow of degradedmaterial away from t

According to another aspect the invention there is provided a vascularfilter comprising:

one or more capture members, the one or more capture members beingmovable from a capturing position to an open position, in the capturingposition the one or more capture members being configured to capturethrombus passing through a blood vessel, in the open position the one ormore capture members being configured to facilitate unrestricted bloodflow, andmeans to hold the one or more capture members in the capturing position.

By capturing the thrombus, the filter prevents the thrombus from passingto the heart or lungs, which may cause pulmonary embolism. By supportingthe capture members this ensures that the capture members are maintainedin the desired location in the blood vessel.

In one embodiment of the invention the capture member is biased towardsthe open position. Preferably the holding means is configured totemporarily hold the capture member in the capturing position untilelapse of a predetermined period of time. The predetermined period oftime may be between approximately 4 months and approximately 24 months.Ideally at least part of the holding means is biodegradable and/orbioabsorbable. All of the holding means may be biodegradable and/orbioabsorbable. At least part of the holding means may be biostable. Mostpreferably the holding means comprises one or more predetermined failurepoints.

In another embodiment at least part of the holding means engages withthe capture member to hold the capture member in the capturing position.

In one case at least part of the holding means extends through anopening in the capture member to hold the capture member in thecapturing position. The filter may comprise a plurality of capturemembers, and in the capturing position the capture members are arrangedwith the openings in the capture members circumferentially spaced apart.In the capturing position the opening in the capture member may facecircumferentially. This arrangement enables the holding means to passsmoothly from one opening to the next opening. Preferably in thecapturing position the holding means comprises a first element extendingthrough the opening in the capture member and a second element tomaintain the first element extending through the opening in the capturemember. Ideally in the capturing position the second element connects afirst end of the first element to a second end of the first element.Most preferably the first element is biostable. The second element maybe biodegradable and/or bioabsorbable.

The radial dimension of the capture member radially inwardly of theopening may be greater than the radial dimension of the capture memberradially outwardly of the opening. At least part of the opening may havea chamfered edge. In this manner any inadvertent wear or damage to theholding means is avoided.

In another case the holding means comprises a first element connected toa second element at a connection point, the first element extending fromthe connection point through an opening in a first capture member, andthe second element extending from the connection point through anopening in a second capture member. Preferably the element extendssubstantially radially from the connection point through the opening inthe capture member.

The filter may comprise a plurality of capture members, and in thecapturing position the capture members are arranged with the openings inthe capture members aligned in a straight line. In the capturingposition the openings in the capture members may be alignedlongitudinally in a straight line. In the capturing position theopenings in the capture members may be aligned radially in a straightline. In one embodiment the longitudinal axis of the holding means issubstantially straight. Preferably a first end of the holding means isdisconnected from a second end of the holding means. Ideally at leastpart of the holding means is formed integrally with the capture member.The holding means may engage with the internal wall of the opening ofthe capture member. The holding means may engage with the capture memberexternally of the opening. Most preferably the holding means issubstantially rigid. The holding means may comprise at least one pinelement. The pin element may comprise a central element extendablethrough the opening in the capture member, and at least one stop elementat an end of the central element externally of the opening. The pinelement may comprise a first stop element at a first end of the centralelement and a second stop element at a second end of the centralelement. The stop element may be formed separately to the centralelement. The stop element may be formed integrally with the centralelement. At least part of the stop element may be biodegradable and/orbioabsorbable. At least part of the stop element may be biostable. Atleast part of the central element may be biostable. At least part of thecentral element may be biodegradable and/or bioabsorbable.

In another embodiment the holding means extends around at least part ofthe capture member to hold the capture member in the capturing position.The holding means may comprise a ring element. The holding means maycomprise a tube element. At least part of the holding means may besubstantially conically shaped. At least part of the holding means maycomprise a mesh. Preferably the holding means is located proximally ofthe distal end of the capture member. Ideally the holding meanscomprises a first opening through which a first set of one or morecapture members extends in the capturing position, and a second openingthrough which a second set of one or more capture members extends in thecapturing position. Most preferably the first set of one or more capturemembers extends through the first opening in the open position. In thismanner the holding means is coupled to the first set of one or morecapture members in the open position. The wall thickness of the holdingmeans around the first opening may be greater than the wall thickness ofthe holding means around the second opening. This arrangement results infailure of the holding means occurring at the second opening.

In one case the filter is configured to couple the holding means to thecapture member in the capturing position. This arrangement prevents anyinadvertent movement of the holding means relative to the capture memberin the capturing position. Preferably the filter is configured to couplethe holding means to the capture member in the open position. Thisarrangement prevents any inadvertent movement of the holding meansrelative to the capture member in the open position. Ideally the capturemember comprises at least one bend to couple the holding means to thecapture member. Most preferably the angle of the bend is greater than 60degrees.

At least part of the capture member may be twisted.

In another case the filter comprises a vena cava filter.

In another aspect of the invention there is also provided a method ofmanufacturing a vascular filter, the method comprising the step ofengaging a holder member with one or more capture members to hold theone or more capture members in a capturing position.

In one embodiment of the invention the method comprises the step ofextending at least part of the holder member through an opening in thecapture member. Preferably the method comprises the step of connecting afirst end of the holder member to a second end of the holder member tomaintain the holder member extending through the opening in the capturemember. The holder member may comprise a central element extendablethrough the opening in the capture member, and at least one stop elementat an end of the central element externally of the opening. The centralelement and the stop element may be formed integrally. Preferably themethod comprises the step of deforming the holder member to form thecentral element and the stop element. The central element and the stopelement may be formed separately. Preferably the method comprises thestep of attaching the stop element to the central element.

In another embodiment the method comprises the step of extending theholder member around at least part of the capture member.

In this specification the terms “filter element”, “capture member”, and“capture arm” are used interchangeably all to mean a part of a filter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingdescription of some embodiments thereof, given by way of example only,with reference to the accompanying drawings, in which:

FIG. 1( a) is a side view of a vascular filter device according to theinvention in a blood vessel, and FIG. 1( b) is an enlarged isometricview showing a holder member of this device;

FIGS. 2 and 3 are diagrams showing deployment of the device of FIG. 1,and FIGS. 4 to 8 show this device in use;

FIG. 8( a) is a side view of part of another vascular filter deviceaccording to the invention, FIG. 8( b) is an end view of this device,FIGS. 8( c) and 8(d) are isometric views of part of this device, FIG. 8(e) is an end view of this device, and FIG. 8( f) is an enlargedisometric view of part of this device;

FIG. 9 is an isometric view of another vascular filter device accordingto the invention during manufacture,

FIG. 10 is an isometric view of this device after manufacture,

FIG. 11 is an enlarged isometric view of part of this device,

FIG. 12 is a view similar to FIG. 11 of another vascular filter deviceaccording to the invention,

FIG. 13 is a perspective view similar of a holder member of anothervascular filter device according to the invention,

FIG. 14 is an end view of the device of FIG. 13,

FIGS. 15 and 16 are isometric views of part of the device of FIG. 13during manufacture,

FIG. 17 is a perspective view of another vascular filter deviceaccording to the invention,

FIG. 18 is an isometric view of part of the device of FIG. 17,

FIG. 19 is an isometric view of another part of this device,

FIG. 20 is an end view of this device;

FIG. 20( a) is an end view of part of another vascular filter deviceaccording to the invention,

FIG. 21 is a perspective view of a holder arrangement of anothervascular filter device according to the invention,

FIGS. 22 and 23 are isometric views of parts of this device duringmanufacture,

FIG. 24 is a perspective view of the holder arrangement of anothervascular filter device of the invention, and

FIG. 25 is an end view of part of this device,

FIG. 26 is an isometric view of part of another vascular filter deviceof the invention,

FIG. 27 is an isometric view of another vascular filter device of theinvention,

FIG. 28 is an isometric view of part of this device,

FIG. 29 is a side view of another part of this device

FIG. 30 is a side view of part of another vascular filter device of theinvention,

FIGS. 31 to 34 are isometric views of parts of this device duringmanufacture,

FIG. 34( a) is a view similar to FIG. 30 of another vascular filterdevice of the invention, and FIG. 34( b) is an enlarged side view ofpart of this device,

FIG. 35 is a perspective view of another vascular filter device of theinvention,

FIG. 36 is an end view of part of this device,

FIG. 37 is a side view of part of this device,

FIG. 38 is an enlarged, cross-sectional side view of part of thisdevice,

FIG. 38( a) is a perspective view of another vascular filter device ofthe invention,

FIGS. 38( b) to 38(e) are isometric views illustrating manufacture ofanother vascular filter device according to the invention,

FIG. 38( f) is a perspective view of another vascular filter device ofthe invention, FIGS. 38( g) and 38(h) are isometric views of parts ofthis device FIG. 38( i) is an isometric view illustrating manufacture ofthis device,

FIG. 39 is an isometric view of part of another vascular filter deviceof the invention,

FIGS. 39( a) to 39(c) are views similar to FIG. 39 of parts of othervascular filter devices of the invention,

FIG. 40 is a view similar to FIG. 30 of another vascular filter deviceof the invention,

FIG. 41 is a view similar to FIG. 30 of another vascular filter deviceof the invention,

FIG. 42 is an enlarged, cross-sectional side view of part of thevascular filter device of FIG. 41,

FIG. 42( a) is a perspective view of another vascular filter device ofthe invention, FIG. 42( b) is a plan view of part of this device, FIG.42( c) is a view along line A-A in FIG. 42( b),

FIG. 42( d) is a cross sectional side view of part of another vascularfilter device of the invention,

FIG. 43 is an isometric view from the front of part of another vascularfilter device of the invention,

FIG. 44 is an isometric view from the rear of this device,

FIGS. 45 to 47 are isometric views of part of this device duringmanufacture,

FIG. 48 is a perspective view of another vascular filter of theinvention, and

FIG. 49 is a view along line A-A in FIG. 48;

FIG. 50 is a perspective view of another vascular filter device of theinvention, and

FIG. 51 is an isometric view of part of the vascular filter device ofFIG. 50;

FIG. 52 is a perspective view of the ends of filter elements,

FIG. 53 illustrates a holder insert and housing for use with thesefilter elements, and

FIGS. 54 to 56 are views showing connection of the holder parts;

FIG. 57 is a cross-sectional view showing a holder assembly with aflexible pin tied at both ends;

FIGS. 58 and 59 are cross-sectional views showing a holder assembly witha heat shrink tube;

FIGS. 60 to 62 are diagrammatic side views showing insertion of a holderclawed pin into place through the ends of filter elements;

FIG. 63 is a cross-sectional view showing a holder assembly having apre-tapered pin inserted through the ends of filter elements;

FIGS. 64 to 67 is a set of perspective views showing connection of aholder assembly having a twist lock arrangement;

FIGS. 68 to 70 are perspective views of alternative holder members;

FIGS. 71 and 72 are perspective views of an alternative holder assembly,in which a holder cap fits over ridges in the ends of filter elements;

FIGS. 73 and 74 are partly cut-away side views showing a still furtherholder assembly of the invention, in which filter element ends snap fitinto a holder cap;

FIG. 75 is a cross-sectional view showing a holder assembly having abiodegradable tube snap-fitted over ridges;

FIGS. 76 and 77 are views of a further holder assembly having a tube toallow washing away of acids produced during degradation, and

FIG. 78 shows an alternative assembly to achieve this;

FIG. 79 is a set of diagrams showing in-situ moulding of a holder pin;and

FIG. 80 is a set of views showing engagement of bent-over filter elementends around holder rings.

DETAILED DESCRIPTION

Referring to the drawings, and initially to FIGS. 1 to 8 thereof; thereis illustrated a vascular filter device 1 according to the invention.

The device 1 is suitable for use as an inferior vena cava filter in theinferior vena cava 2. The device 1 is movable from a capturing position(FIG. 4) to an open position (FIG. 7) upon elapse of a predeterminedperiod of time. In the capturing position the device 1 is configured tocapture thrombus passing through the inferior vena cava 2 towards theheart and the lungs (FIG. 5). The device 1 may thus be used to preventpulmonary embolism. In the open position the filter 1 is configured tofacilitate unrestricted blood flow.

As illustrated in FIG. 1, the device 1 comprises a proximal support hoop3 at the proximal end of the device 1, a distal support hoop 4 at thedistal end of the device 1, and a plurality of support struts 5extending between the proximal support hoop 3 and the distal supporthoop 4.

In this patent specification, the terms ‘proximal’ and “distal” are usedin the sense that a proximal part is upstream of a distal part withreference to the direction of blood flow.

The proximal support hoop 3 comprises a wire element which extendscircumferentially around the internal wall of the inferior vena cava 2in a sinusoid wave pattern. Similarly the distal support hoop 4comprises a wire element which extends circumferentially around theinternal wall of the inferior vena cava 2 in a sinusoid wave pattern.The support struts 5 extend longitudinally along the internal wall ofthe inferior vena cava 2. The support struts 5 connect the proximalsupport hoop 3 to the distal support hoop 4. In this case the proximalsupport hoop 3, the distal support hoop 4 and the support struts 5 areformed integrally. The proximal support hoop 3, the distal support hoop4 and the support struts 5 may be of a shape-memory material, such asNitinol™.

The device 1 is movable between a collapsed delivery position and anexpanded deployed position. The device 1 is biased radially outwardlytowards the deployed position. When the device 1 is deployed in theinferior vena cava 2, the support hoops 3 and 4 exert a force radiallyoutwardly on the internal wall of the inferior vena cava 2. In thismanner the support hoops 3 and 4 support the filter elements 6 inposition relative to the wall of the inferior vena cava 2.

As illustrated in FIG. 1, the device 1 comprises twelve filter elements6 for capturing thrombus passing through the inferior vena cava 2. Eachfilter element 6 is formed integrally with the proximal support hoop 3.An opening 13 is provided at the distal end of each of the filterelements 6 (FIG. 1( a)).

The filter elements 6 are movable from the capturing position (FIG. 4)to the open position (FIG. 7) upon elapse of the predetermined period oftime. In the capturing position the filter elements 6 are configured tocapture thrombus passing through the inferior vena cava 2 towards theheart and the lungs (FIG. 5). In the open position the filter elements 6are configured to facilitate unrestricted blood flow.

In the capturing position the filter elements 6 extend in asubstantially straight line to an apex 7. In this manner the filterelements 6 define a generally conically shaped capture region 8 withinwhich thrombus may be captured. When the device 1 is deployed in theinferior vena cava 2, the apex 7 is substantially in-line with thelongitudinal axis extending through the centre of the inferior vena cava2, and the capture region 8 is located in the region of the centre ofthe inferior vena cava 2. When the device 1 is deployed in the inferiorvena cava 2, the filter elements 6 extend in the direction of blood flowthrough the inferior vena cava 2.

In the capturing position the filter elements 6 are arranged with theopenings 13 circumferentially spaced apart in a loop (FIG. 1( a)).

The distal end of the distal support hoop 4 is located distally of thefilter elements 6 and the apex 7, and the proximal end of the proximalsupport hoop 3 is located proximally of the filter elements 6.

The filter elements 6 are movable from the capturing position to theopen position upon elapse of the predetermined period of time. Thefilter elements 6 are biased towards the open position.

As illustrated in FIG. 1( b), the device 1 comprises a holder member 10at the distal ends of the filter elements 6 to temporarily hold thefilter elements 6 in the capturing position until elapse of thepredetermined period of time. The predetermined period of time may bebetween approximately 4 months and approximately 24 months. The holdermember 10 comprises a flexible wire element 12 which extends in a loopthrough the opening 13 in each filter element 6, and a stop element 11.The wire element 12 engages with each filter element 6 to hold thefilter elements 6 in the capturing position. In the capturing positionthe stop element 11 is fixedly attached to each end of the wire element12 and thus connects each end of the wire element 12 together. In thismanner the stop element 11 maintains the wire element 12 extendingthrough the openings 13 in the filter elements 6.

The wire element 12 is biostable, and the stop element 11 isbiodegradable and/or bioabsorbable upon elapse of the predeterminedperiod of time. Upon biodegrading/bioabsorbing of the stop element 11,the filter elements 6 are free to move from the capturing position tothe open position. The filter elements 6 are not biodegradable orbioabsorbable.

The flexible biostable wire 12 is used to tie the filter elements 6together. The ends of the flexible biostable element 12 are secured withthe biodegradable component 11. The biodegradable element 11 may beover-moulded, snap fitted, bonded, or crimped onto the biostable ends.The wire 12 may be looped around one of the eyelets 13 to ensure thatthe wire 12 moves with the eyelets 13 to the vessel wall upon conversionrather than becoming an embolus.

During manufacture of the vascular device 1, the wire element 12 isextended through the openings 13. The stop element 11 is fixedlyattached to each end of the wire element 12 to connect each end of thewire element 12 together. In this manner the wire element 12 ismaintained extending through the openings 13. The wire element 12engages with the filter elements 6 to hold the filter elements 6 in thecapturing position.

In use the device 1 is collapsed to the delivery configuration, and atleast partially loaded into a delivery catheter. The delivery catheteris advanced through the inferior vena cava 2 until the collapsed device1 reaches the desired location in the inferior vena cava 2 (FIG. 2). Arestraining sheath of the delivery catheter is then moved proximallyrelative to the device 1 to fully uncover the device 1 (FIG. 3). Due tothe biasing nature of the device 1, it moves from the collapsed deliveryconfiguration to the expanded deployed configuration (FIG. 4). In thedeployed configuration, the support hoops 3, 4 exert a radially outwardforce on the internal wall of the inferior vena cava 2 to support thefilter elements 6 in the desired position in the inferior vena cava 2.

In the event of thrombus passing through the inferior vena cava 2towards the heart and the lungs, the thrombus will be captured in thecapture region 8 of the device 1 (FIG. 5). The thrombus will thus beprevented from passing into the heart and the lungs which couldotherwise lead to pulmonary embolism. The captured thrombus willgradually be broken down by the body into smaller size particles whichwill significantly reduce the hazardous effects of embolism (FIG. 6).

The holder member 10 temporarily holds the filter elements 6 in thecapturing position until elapse of the predetermined period of time.Upon elapse of the predetermined period of time the stop element 11biodegrades/bioabsorbs. This enables the filter elements 6 to move fromthe capturing position to the open position (FIG. 7). In the openposition the device 1 facilitates unrestricted blood flow. The supporthoops 3 and 4, and the filter elements 6 remain in the inferior venacava 2 (FIG. 8). If the holder 10 incorporates a biostable element 12,the biostable element is preferably coupled to one of the filterelements and therefore remains in the vena cava 2.

In FIGS. 8( a) to 8(f) there is illustrated another vascular filterdevice 180 according to the invention, which is similar to the vasculardevice 1 of FIGS. 1 to 8, and similar elements in FIGS. 8( a) to 8(f)are assigned the same reference numerals.

In this case in the capturing position each filter element 6 extends ina substantially straight line to the apex 7. Each filter element 6 istwisted through 90 degrees before the apex 7 (FIG. 8( c)).

An opening 13 is provided at the distal end of each of the filterelements 6. The radial dimension of the filter element 6 radiallyinwardly of the opening 13 is greater than the radial dimension of thefilter element 6 radially outwardly of the opening 13 (FIG. 8( c)). Inparticular the thickness of the wall 183 of the filter element 6radially inwardly of the opening 13 is greater than the thickness of thewall 184 of the filter element 6 radially outwardly of the opening 13.The radially inward side of the opening 13 has a chamfered edge 182(FIG. 8( d)).

In the capturing position the filter elements 6 are arranged with theopenings 13 in the filter elements 6 circumferentially spaced apart in aloop (FIG. 8( b)). In the capturing position each opening 13 facescircumferentially.

The holder member comprises two sutures 181 which extend in two loopsthrough the opening 13 in each filter element 6. The sutures 181 engagewith each filter element 6 to hold the filter elements 6 in thecapturing position. Each suture 181 is biodegradable and/orbioabsorbable upon elapse of the predetermined period of time. All ofthe suture 181 is biodegradable and/or bioabsorbable. Uponbiodegrading/bioabsorbing of the sutures 181, the filter elements 6 arefree to move from the capturing position to the open position. Thefilter elements 6 are not biodegradable or bioabsorbable.

The eyelets 13 are twisted by 90° to achieve a smoother threading pathfor the monofilament 181 used to tie the filter elements 6.

The eyelets 182 are chamfered/rounded to create a smoother path for anymovement of the monofilament 181 and to prevent any damage by mechanicalwear. The eyelet hole 13 is offset to ensure that the monofilament 181moves against the thicker, smoother surface 182. For a given outereyelet width, an offset opening allows for a larger rounded or chamfereddimension. A larger rounded or chamfered dimension reduces sharpness sothat it does not act as a cutting edge.

Two lengths of monofilament 181 are used to secure the filtrationelements 6 for extra security. A stopper knot is tied on top of one ofthe eyelets 13 to further reduce the effect of movement/mechanical wear.This eyelet feature 13 provides an anchor point for the knot onconversion of the device 180.

In FIGS. 9 to 11 there is illustrated another vascular filter device 20according to the invention. In this case the holder member comprises aring element 21 extending around the filter elements 22 to hold thefilter elements 22 in the capturing position until elapse of thepredetermined period of time. The ring element 21 is biodegradableand/or bioabsorbable upon elapse of the predetermined period of time.

The distal end of each filter element 22 comprises a bend (FIG. 11). Theangle of each bend is approximately 135 degrees in this case. The bendat the distal end of each filter element 22 acts as a hook element tocouple the ring element 21 to the filter elements 6 in the capturingposition.

During manufacture of the vascular device 20, the ring element 21 isextended around the filter elements 22. The ring element 21 engages withthe filter elements 22 to hold the filter elements 22 in the capturingposition.

The device 1 consists of the Nitinol™ filter elements 22 and thebiodegradable material 21. The circular ring 21 which secures the filterelements 22 is uninterrupted and has a consistent cross-sectional areathroughout. Use of the ring 21 decreases production time and eliminateshuman error and inconsistency when securing the filter elements 6.

To prevent the ring 21 being displaced during physiological movements,the proximal ends of the filter elements 22 are shaped to encircle thering 21. The ring 21 is applied by initially bringing the filterelements 22 together, as shown in FIG. 9. The ring 21 is placed over thefilter elements 22. When the filter elements 22 are no longer detainedin place, they will retract towards the filter wall applying tension tothe ring 21. To prevent migration of the ring 21 during physiologicalmovements, it is secured by forming the proximal end of the filterelements 22 through heat setting or plastic deformation, as shown inFIGS. 10 and 11.

To assemble, the filter arms 6 are medially brought together, and thering 21 of degradable material is placed over the elements 6 (FIG. 9).The filter elements 22 are closed in around the ring 21 to prevent ringmigration (FIG. 10).

Using the ring 21 may prevent potential long-term failures such as theholder member unravelling and failure due to excessive tightening of theholder member. The ring 21 provides consistency between manufacturedunits of the device 20 by eliminating operator variation associated withknot tying. More than one ring may be used to increase the forcerequired to break the holder, this will lengthen the time to failure andalso act as a safety feature in the event that one ring is damaged.

An alternative embodiment is shown in FIG. 12 where the ring 21 isapplied inside filter elements 23 from underneath.

FIGS. 13 to 16 illustrate a further vascular device 30 according to theinvention. The device 30 has filter elements 31 with a radially-directedslot or notch 32 at a bend in the filter elements 31, the angle of eachbend being approximately 90°.

A possible method of manufacturing the device 30 includes machining thenotch 32 in at the distal end of the filter element 31 as shown in FIG.15. The tip of the filter arm 31 is then heat-set in a shape similar tothat shown in FIG. 16. The filter element arms 6 can then be constrainedtogether in a filtering position using the polymeric O-ring 33 as shownin FIG. 13.

Manufacture of the device 30 using the O-ring 33 is easy, rapid andrepeatable. Using the O-ring 32 allows for easy control of the diameterof the lumen which is at the tips of the filter elements 31 on thedevice 30, as shown in FIG. 14. This lumen allows for flow of blood topass through the apex 35 of the device 30 and avoids generating an areaof stagnation within the device 30 in this region.

FIG. 13 illustrates the degradable retaining ring 33 in place, FIG. 14illustrates an end view of the device 30 showing the lumen at the apex35, FIG. 15 illustrates the strut with the notch created, and FIG. 16illustrates the strut heat-set into position.

Referring to FIGS. 17 to 20 there is illustrated another vascular filterdevice 40 according to the invention. In this case a holder member 41comprises six arms 42. The six arms 42 are connected together at acentral connection point 43. Each arm 42 extends radially from theconnection point 43 through an opening 45 in a filter element 46. Eacharm 42 engages with a filter element 46 to hold the filter elements 46in the capturing position.

The holder member 41 is biodegradable and/or bioabsorbable upon elapseof the predetermined period of time. Upon biodegrading/bioabsorbing ofthe holder member 41, the filter elements 46 are free to move from thecapturing position to the open position.

The moulded biodegradable component 41 is in the form of a snow-flakeand may be incorporated to restrain the filter elements 46.

The eyelets 45 at the distal ends in their heat-set form are provided asa closed ‘C’-shape. The eyelet 45 is then chilled below the Mftemperature and mechanically spread to open the eyelet 45 wider. Themoulded component 41 is inserted and the opened eyelet 45 is closedthrough application of heat to secure the moulded component 41 to theeyelets 45.

As illustrated in FIG. 20( a), the holder member may be provided withone wider strut 44. The wider strut 44 having an increased tensilestrength will fail post failure of the other five thinner struts 42. Aseach of the thinner struts 42 fails, the T-shaped head and failed strutportion are carried to the vessel wall by the eyelet 13 where it becomesendotheliased. The eyelet 45 holding the wider strut 44 carries theremaining material to the vessel wall where it becomes endotheliasedthus preventing it from becoming an embolus. Ideally, the holder memberhas a strut for each eyelet.

In FIGS. 21 to 23 there is illustrated another vascular device 50according to the invention. In this case a holder member comprises atube element 51 extending around the filter elements 52 to hold thefilter elements 52 in the capturing position until elapse of thepredetermined period of time. The tube element 51 is located proximallyof the distal end of the filter elements 52. The tube element 51 isbiodegradable and/or bioabsorbable upon elapse of the predeterminedperiod of time.

The distal end of each filter element 52 comprises a bend. The angle ofeach bend is approximately 90° in this case. The bend at the distal endof each filter element 52 acts as a hook element to couple the tubeelement 51 to the filter elements 52 in the capturing position.

The biodegradable cap 51 is threaded over the apex region of the filterelements 52 (FIG. 23). Once in position, the ends of the filter elements52 are formed to hold the cap 51 in place. Alternatively, the ends ofthe filter elements are preformed to hold the cap in place and arestraightened mechanically to fit the cap 51. The cap 51 enablessimultaneous opening upon conversion.

Other tubular cross sections or an O-ring may be used in place of thecap 51.

FIGS. 24 and 25 illustrate a further vascular filter device 60 accordingto the invention. In this case the holder member comprises a tubeelement 61 extending around the filter elements 6 to hold the filterelements 6 in the capturing position until elapse of the predeterminedperiod of time. The tube element 61 comprises a first opening 62 throughwhich one filter element 64 extends in the capturing position, and asecond opening 63 through which all of the other filter elements 6extend in the capturing position.

The distal end of the filter element 64 comprises a bend. The angle ofthe bend is approximately 135 degrees in this case. The bend at thedistal end of the filter element 64 acts as a hook element to couple thetube element 61 to the filter element 64 in the capturing position.

The tube element 61 is biodegradable and/or bioabsorbable upon elapse ofthe predetermined period of time. The wall thickness of the tube element61 around the first opening 62 is greater than the wall thickness of thetube element 61 around the second opening 63. In this manner the thinnedwall acts as a predetermined failure point. Uponbiodegrading/bioabsorbing of the tube element 61, the tube element 61will fail around the second opening 63.

Because the tube element 61 does not fail around the first opening 62,the filter element 64 extends through the first opening 62 in the openposition. The bend at the distal end of the filter element 64 acts as ahook element to couple the tube element 61 to the filter element 64 inthe open position.

The multi-lumen cap 61 has the two lumens: the small lumen 62 to housethe filter element 64 or a pair of filter elements surrounded by a largewall thickness, and the large lumen 63 to house the remainder of thefilter elements 64 surrounded by a thin wall thickness.

The tube element 61 has a reduced tensile strength at the failure point.The thin wall has the reduced tensile strength, providing thepredetermined failure point. The filter elements 6 extending through thelarge lumen 63 break the thin wall after the predetermined period oftime and revert to the vessel wall. The filter element 64 extendingthrough the small lumen 62 carries the cap 61 to the vessel wall whereit is bioresorbed thus preventing it from becoming an embolus.

The ending extending through the small lumen 62 is provided with afeature to prevent the cap 61 from dislodging during use. This may beachieved in a number of methods such as forming, bonding, overmoulding,crimping. Features may be provided to secure the remainder of theendings in the large lumen 63.

The multilumen cap 61 enables simultaneous opening upon conversion.

It will be appreciated that a variety of types of multilumen form may beused, as illustrated in FIG. 26. This drawing shows a cylindrical holderelement 66 having a small lumen 67 formed by a curved wall, theremainder of the inside of the element 66 being the large lumen.

More than two lumens may be used. For example, three lumens are providedradially in-line, the central lumen having a thinner wall than the outerlumens on either side. Radially opposing filter elements extend throughthe outer lumens and are secured, the remaining filter elementsextending through the central lumen where they may be temporarilysecured. The thin wall of the central lumen degrades first allowing theradially opposing filter elements to break the holder member into twohalves, each halve being secured to the opposing filter elements postconversion at the vessel wall where biodegradation is completed.

Referring to FIGS. 27 to 29 there is illustrated another vascular filterdevice 70 according to the invention. In this case the holder membercomprises a conically shaped tube element 71 extending around the filterelements 72 to hold the filter elements 72 in the capturing positionuntil elapse of the predetermined period of time. The tube element 71comprises a mesh and is biodegradable and/or bioabsorbable upon elapseof the predetermined period of time.

The distal end of each filter element 72 comprises a bend which acts asa hook to couple the tube element 71 to the filter elements 72 in thecapturing position.

The filter elements 72 are of Nitinol™ and the holder 71 is ofbiodegradable material in the configuration of a profiled sheath tosecure the filter elements 72. The sheath 71 comprises a mesh with atapered thickness, decreasing from proximal to distal, so that theholder degrades radially inwardly to minimise the torque at the formedfilter element ends. Use of the sheath 71 decreases production time andeliminates human error and inconsistency when securing the filterelements 72. Should any of the mesh struts fail, the structuralintegrity of the sheath 71 is not compromised as there are numerousother mesh struts to withstand the radial load.

To prevent the sheath 71 becoming displaced during physiologicalmovements, the distal ends of the filter elements 72 are shaped toencircle the sheath 71.

The sheath 71 is applied by initially bringing the filter elements 72together medially, as shown in FIG. 29. The sheath 71 is then placedover the filter elements 72. When the filter elements 72 are no longerdetained in place, they will retract towards the filter wall applyingtension to the sheath 72. To prevent migration of the sheath 72 duringphysiological movements, the distal end of the eyelets are closed in tosecure the sheath 71, as shown in FIG. 27. If the filter element endsare pre-formed to encircle distal end of the sheath, they must bestraightened temporarily before the sheath is fitted. The proximal endof the sheath 71 may also be secured to one or more of the filter arms72 in the open configuration.

Using the sheath 71 may prevent potential long-term failures. The sheath71 provides consistency between manufactured units of the device 70 byeliminating operator variation associated with knot tying. Themulti-strut mesh architecture ensures maximum structural integrity.

In FIGS. 30 to 34 there is illustrated another vascular filter device 80according to the invention. In this case the holder comprises a rigidpin element 81. The upper end of the pin element 81 is disconnected fromthe lower end of the pin element 81. The pin element 81 comprises anelongate central element 83, an upper stop element 84, and a lower stopelement 82. The lower stop element 82 is formed separately to thecentral element 83. The upper stop element 84 is formed separately tothe central element 83.

In the capturing position the filter elements 85 are arranged with theopenings 86 in the filter elements 85 aligned radially in a straightline (FIG. 30). As illustrated in FIGS. 31 to 34, a portion of the wallof the filter element 85 extends around the full circumference of eachopening 86 to define the opening 86.

The longitudinal axis of the pin element 81 is straight. The centralelement 83 extends in a straight line through the opening 86 in eachfilter element 85 with the upper stop element 84 at the upper end of thecentral element 83 externally of the openings 86, and the lower stopelement 82 at the lower end of the central element 83 externally of theopenings 86.

In the capturing position the upper stop element 84 engages with theupper filter element 85 externally of the opening 86, and the lower stopelement 82 engages with the lower filter element 85 externally of theopening 86. In this manner the filter elements 85 are held in thecapturing position.

The central element 83 is biostable, and the stop elements 84, 82 arebiodegradable and/or bioabsorbable upon elapse of the predeterminedperiod of time. Upon biodegrading/bioabsorbing of the stop elements 84,82, the filter elements 85 are free to move from the capturing positionto the open position.

The two stops 84, 82 may be biostable if a biodegradable pin 83 is used.It is appreciated that only one component needs to be biodegradable.Alternatively, the two stops 84, 82, and the pin 83 can bebiodegradable.

During manufacture of the vascular device 80, each stop element 84, 82is attached to the central element 83. Attachment of the secondaryholder member 84, 82 to the pin 83 may be through crimping, or bonding,or overmoulding, or a mechanical snap fit, or a screw thread, or solventbonding.

A possible method of attaching the central element 83 within an eyelet86 of the device 80 is illustrated in FIGS. 31 to 34. The long slendereyelet 86 is formed as shown in FIG. 31. The eyelet 86 in the heat-setshape is narrower than the central element 83 that is being attached tothe eyelet 86. The eyelet 86 is chilled below the Mf temperature andmechanically spread to open the eyelet 86 wider, making it closer to acircular opening as shown in FIG. 32. The central element 83 ispositioned within the eyelet 86 as shown in FIG. 33. The eyelet 86 isheated above its Af temperature so that the eyelet 86 retakes its memoryshape. As the eyelet 86 returns to its memory shape it will form aninterference fit between the eyelet 86 and the central element 83positioned within the eyelet 86. Alternatively, the openings aremachined wide and are crimped onto the central element 83 to secure thefilter elements in the capturing position.

It will be appreciated that the pin element 81 may be flexible asillustrated by a pin element 91 in FIGS. 34( a) and 34(b).

The eyelets 86 of the filter elements 85 may be arranged to apply a bendto the straight pin 81. In this case the pin 81 has enough flexibilityto bend. Alternatively, the pin 81 may be moulded with the curvaturepreset.

Referring to FIGS. 35 and 36 there is illustrated another vasculardevice 100 according to the invention. The device 100 comprises filterelements 105 with eyelets 106. In this case a first stop element 102 isformed integrally with a central element 103. A second stop element 104is formed separately to the central element 103.

The central element 103 and the first stop element 102 are biostable,and the second stop element 104 is biodegradable and/or bioabsorbableupon elapse of the predetermined period of time. Uponbiodegrading/bioabsorbing of the second stop element 104, the filterelements 105 are free to move from the capturing position to the openposition.

During manufacture of the vascular device 100, the pin element isdeformed to form the central element 103 and the first stop element 102.

Either end of the pin may be formed to secure the filter elements 105 inthe capturing position, for example through mechanical methods toachieve a dumbbell shape or rivet, through heat, or with a solvent.

The pin element provides a rigid holder member for longer termfiltration for example approximately 4 to 24 months until degradation.It may be a moulded piece.

An opening 106 in the end of each capture member 105 is aligned to allowinsertion of the pin with the integral cap. Once the pin is in place,the end with no cap is secured with the biodegradable stop. Whendeployed, the filter elements 105 are retained in the filteringposition. After a certain period of time, the biodegradable stop 104weakens to a failure mode where the radial force of the filter elements105 overcomes the coupling force between the pin central element 103 andthe stop 104.

The pin may be manufactured from a biostable flexible or rigid material.In this case, the biodegradable stop 104 weakens and the filter elements105 revert to their radially biased position at the vessel wall. Theopening 106 in the filter element 105, traps the pin against the vesselwall where it becomes endothelised.

Alternatively the stop may be manufactured from a biostable material, inwhich case the pin would be biodegradable.

Using the pin 101 allows simultaneous opening of the filter elements105.

FIGS. 37 and 38 show a variation, in which like parts are assigned thesame reference numerals. In this case a stop element 108 is positionedonto the pin central element 103 which extends past the stop element.

In FIG. 38( a) there is illustrated another vascular device 110according to the invention. In this case a holder member comprises tworigid pin elements 111. The upper end of each pin element 111 isdisconnected from the lower end of each pin element 111. Each pinelement 111 comprises an elongate central element 113, an upper stopelement 114, and a lower stop element. Each upper stop element 114 isformed separately to each central element 113. The first upper stopelement 114 is formed integrally with the second upper stop element 114.

The lower end of the first central element 113 is connected to the lowerend of the second central element 113 in a loop 115. The first centralelement 113 is formed integrally with the second central element 113. Byconnecting together the lower ends of the two central elements 113 inthe loop 115, this loop 115 acts as a lower stop element for each pinelement 111.

Two openings 117 are provided at the distal end of each of the filterelements 116. Each central element 113 extends in a straight linethrough an opening 117 in each filter element 116.

In the capturing position each upper stop element 114 engages with theupper filter element 116 externally of the openings 117, and the lowerstop loop 115 engages with the lower filter element 116 externally ofthe openings 117. In this manner the filter elements 116 are held in thecapturing position.

The central element 113 is biostable, and the upper stop elements 114are biodegradable and/or bioabsorbable upon elapse of the predeterminedperiod of time. Upon biodegrading/bioabsorbing of the upper stopelements 114, the filter elements 116 are free to move from thecapturing position to the open position.

The biostable/biodegradable wires 113 are threaded through the two slots117 so that the upper ends of the wires 113 are aligned. The alignedendings are secured by over-moulding the biodegradable securing features114.

FIGS. 38( b) to 38(e) illustrate a further vascular filter device 120according to the invention. In this case a lower stop element 122 isformed integrally with a central element 123, and the upper stop element124 is formed integrally with the central element 123.

The central element 123 and the stop elements 124, 122 are biodegradableand/or bioabsorbable upon elapse of the predetermined period of time.Upon biodegrading/bioabsorbing of the central element 123 and the stopelements 124, 122, the filter elements 125 are free to move from thecapturing position to the open position.

The T-shaped pin 121 is threaded through the set of elongated eyelets126 (FIGS. 38( b) and 38(c)) and twisted through 90° (FIG. 38( d)). Thetop and bottom eyelets 126 are formed to lock the pin 121 (FIG. 38( e)).

Referring to FIGS. 38( f) to 38(i) there is illustrated another vascularfilter device 130. In this case an opening 138 in the upper filterelement 136 comprises a retainer finger 137, and the opening 138 in thelower filter element 136 comprises a retainer finger 137. Each retainerfinger 137 protrudes radially inwardly into the opening 138.

In the capturing position the upper stop element 134 engages with theretainer finger 137 of the upper filter element 136, and the lower stopelement 132 engages with the retainer finger 137 of the lower filterelement 136. In this manner the filter elements 136 are held in thecapturing position.

The upper stop element 134 is extendable through the opening 138 in thefilter element 136 in a snap-fit manner to pass the retainer finger 137(FIG. 38( i)).

The snap fit feature 137 may be provided in the top and bottom filterelement 136. The snap fit feature 137 allows the T-head 134 to be edgedthrough at an angle but not when fully assembled.

Referring to FIG. 39 a central element 139 may comprise one or moreprotrusions 139(a) which may act as ratchets. Multiple ratchets 139(a)are shown but only one is required for the invention to function. Havingonly one ratchet 139(a) enables simultaneous opening upon conversion.

It will be appreciated that the pin element may be provided in a varietyof possible forms, as illustrated in FIGS. 39( a) to 39(c), pins 139(b),139(c), and 139(d) respectively. The snap fit pin may be provided as asquare, round, or flat geometry.

The flat geometry may be manufactured by laser cutting the shape from asheet of material, or machining the shape from a sheet of material, orstamping the shape from a sheet of material, or extruding the profileand cutting it to the desired thickness.

The square geometry may be manufactured in a similar way. A process maybe required to remove material from the central section. Alternativelythe head and the snap fit features may be formed through heat or plasticdeformation on a square rod. Various rod cross sections may be used. Theround pin may also be manufactured by heat forming a rod of material.Any of the pin element designs disclosed herein may be injectionmoulded.

In FIG. 40 there is illustrated another vascular filter device 140according to the invention. In this case a pin element 141 comprises anelongate central element 143, an upper stop element, and a lower stopelement 142. The central element 143 is formed integrally with the upperfilter element 146. The lower stop element 142 is formed separately tothe central element 143.

The longitudinal axis of the pin element 141 is straight, and thecentral element 143 extends in a straight line through the opening ineach of the other filter elements 146. By connecting together thecentral element 143 and the upper filter element 146 in a bend 147, thisbend 147 acts as an upper stop element for the pin element 141.

In the capturing position the bend 147 engages with the adjacent filterelement 146, and the lower stop element 142 engages with the lowerfilter element 146. In this manner the filter elements 146 are held inthe capturing position.

The central element 143 is biostable, and the lower stop element 142 isbiodegradable and/or bioabsorbable upon elapse of the predeterminedperiod of time. Upon biodegrading/bioabsorbing of the lower stop element142, the filter elements 146 are free to move from the capturingposition to the open position.

The distal end of one of the filter elements 146 is used as the pin 143.Upon conversion, the pin portion 143 may be heat set to extend along thevessel wall rather than extending through the flow.

The stop feature 142 may be attached in a number of methods such ascrimping, bonding, overmoulding, or welding.

FIGS. 41 and 42 illustrate a further vascular filter device 150according to the invention. In this case a pin element 151 comprises anelongate central element 83 without any external stop elements.

In the capturing position a central element 153 engages with theinternal wall of an opening of the upper filter element 156, and engageswith the internal wall of the opening of the lower filter element 156.In this manner the filter elements 156 are held in the capturingposition.

The central element 153 is biodegradable and/or bioabsorbable uponelapse of the predetermined period of time. Uponbiodegrading/bioabsorbing of the central element 153, the filterelements 156 are free to move from the capturing position to the openposition.

The top and bottom openings in the distal ends of the filter elements156 are secured to the biodegradable pin 153. They may be secured by anumber of methods such as bonding, crimping, or welding.

Alternatively the pin 153 may be biostable if a biodegradable materialis overmoulded between the opening and the pin 153 at either end.

Referring to FIGS. 42( a) to 42(c) there is illustrated another vascularfilter device 160 according to the invention. In this case the holdermember comprises two rigid pin elements 163 extending through openings161. Each pin element 163 comprises an elongate configuration withoutany external stop elements.

In the capturing position each central element 163 engages with theinternal wall of the opening 161 of each filter element 166. In thismanner the filter elements 166 are held in the capturing position.

Each central element 163 is biodegradable and/or bioabsorbable uponelapse of the predetermined period of time. Uponbiodegrading/bioabsorbing of each central element 163, the filterelements 166 are free to move from the capturing position to the openposition.

Each eyelet 161 is provided with an opening profile that lines up whenassembled. The bio-degradable material 163 is injected into the openings161 and cured in-situ in the openings 161 to hold the assembly 160together.

In FIG. 42( d) there is illustrated another vascular filter device 300according to the invention. In this case a pin element 301 comprises anelongate central element 303 and a lower stop element 302. The lowerstop element 302 is formed integrally with the central element 303. Thepin element 301 comprises a thread formation 307 at the upper end of thecentral element 303. The opening 13 of the upper filter element 306comprises a corresponding thread formation.

The central element 303 and the lower stop element 302 are biodegradableand/or bioabsorbable upon elapse of the predetermined period of time.Upon biodegrading/bioabsorbing of the central element 303 and the lowerstop element 302, the filter elements 306 are free to move from thecapturing position to the open position.

In the capturing position the thread formation 307 of the centralelement 303 engages with the internal wall of the opening of the upperfilter element 306. In this manner the filter elements 306 are held inthe capturing position.

The thread pattern 307 is incorporated to connect the pin 303 and thetop eyelet. A separate threaded nut may be used instead of threading theeyelet. This nut would secure the filter elements in the capturingposition externally of the adjacent filter element opening.

In FIGS. 43 to 47 there is illustrated another vascular device 170according to the invention. In this case the holder member comprises apin element 171 and a ring element 177.

The pin element 171 comprises an elongate central element 173, an upperstop element, and a lower stop element 172. The central element 173 isformed integrally with the upper filter element 176. The lower stopelement 172 is formed separately to the central element 173.

The longitudinal axis of the pin element 171 is straight, and thecentral element 173 extends in a straight line through an opening 178 inthe lower filter element 176.

By connecting together the central element 173 and the upper filterelement 176 in a bend 177, this bend 177 acts as an upper stop elementfor the pin element 171.

The central element 173 is biostable, and the lower stop element 172 isbiodegradable and/or bioabsorbable upon elapse of the predeterminedperiod of time. The ring element 179 is biostable. Uponbiodegrading/bioabsorbing of the lower stop element 172, the filterelements 176 are free to move from the capturing position to the openposition.

The ring element 179 extends around two of the filter elements 176 tohold these two filter elements 176 in the capturing position untilelapse of the predetermined period of time. In the capturing positionthe bend 177 engages with the ring element 179, and the lower stopelement 172 engages with the lower filter element 176. In this mannerthe filter elements 176 are held in the capturing position.

The apex ring device 170 consists of three types of apex ending: thedouble ring ending, the straight endings, and the long straight ending173. To assemble the filter 170, the large ring 179 is manipulatedthrough 90° (FIG. 47). The large ring 179 is biased to sit at 180°. Thelong ending 173 is manipulated to sit in the crevice of the large ring179 and to extend through the small ring 178. The biodegradable cap 172is attached to the long ending 173 to hold the assembly 170 together.Any number of straight endings 176 can then be manipulated to sit withinthe large ring 179. Upon biodegradation, all endings 176 revert to theirradially outwardly biased position at the vessel wall. The double ring179 and the long ending 173 are biased to extend along the vessel wallrather than into the flow.

The device 170 enables simultaneous opening upon conversion and alsoprovides reduced obstruction to flow. Obstruction may be reduced furtherby increasing the diameter of the large ring 179.

FIGS. 48 and 49 illustrate a further vascular filter device 310according to the invention. In this case in the capturing position thefilter elements 316 are arranged with the openings 318 in the filterelements aligned longitudinally in a straight line (FIG. 49). Thelongitudinal axis of a pin element 311 is straight. The central element313 extends in a straight line through the opening 318 in each filterelement 316.

The pin 311 is orientated to lie along the longitudinal axis of thevessel. This ensures that stresses exerted on the pin 311 areindependent of the orientation that the device 310 is deployed in thevessel. This arrangement also aids in the manufacturing process.

Referring to FIGS. 50 and 51 there is illustrated another vascularfilter device 320 according to the invention. In this case a ‘U’-shapedslot opening 327 is provided at the distal end of each of the filterelements 326. As illustrated in FIG. 51, a portion of the wall of thefilter element 326 extends around only part of the circumference of theopening 327 to define the opening 327.

The eyelets of the device 320 incorporate the open slot 327 to aidinsertion of the pin 321 with caps at either end. As the open slot 327changes orientation for each filter element 326, the pin 321 will besecurely held in position.

Referring to FIGS. 52 to 56, a holder assembly of a device 340 comprisesdistal ends 341 of filter elements and end stops 342. There is abiodegradable holder housing 345 and a biodegradable holder insert 346.The housing fits over the ends 341. The ends 341 are positioned ingrooves 347 of the insert 346 and the stops 342 prevent axial sliding.An interference fit is enough to prevent dis-assembly during use. Themating surfaces of the insert and of the housing may be tapered to alloweasier assembly and a wider tolerance range for the parts. Snap fitprongs may be added to the housing or insert as a double measure toprevent dis-assembly. As the housing slides distally the prongs wouldsnap over the distal face of the insert. Alternatively, the insert mayhave an integral locking thread/feature that engages with a lockingthread/feature on the housing. After the housing is pushed over theinsert, it is rotated relative to the insert to engage the lock. Theinterlocking holder can be adapted for filter elements that end in alinear array rather than the circular array shown. Only one filterelement needs to have a stop feature and to be locked in a groove, theremaining filter element ends need not have the stop feature and couldfloat freely in one or more larger grooves. The holder may have anincreased wall thickness surrounding one of the filter elements oralternative securing member so that the holder remains attached to oneof the filter elements in the open position.

Referring to FIG. 57 a holder assembly 360 has a set of filter elementends 361 with aligned openings 362 through which a flexiblebiodegradable pin 363 extends. There is a tie at each end of the pin363.

Referring to FIG. 58 a holder assembly 380 comprises filter element ends381 with openings 382. A biodegradable pin 383 extends through theopenings and a heat shrink tube 384 fits over the ends of the pin 383. Acircumferential recess 385 helps to retain the tube 384. FIG. 59 shows avariation in which there is a circumferential ridge 388 instead of arecess. Either of the tube and pin may be biodegradable.

Referring to FIGS. 60 to 62 a holder assembly 400 comprises abiodegradable clawed pin 401 having a head 402 and splayed-out claws403. The claws are pressed in to pass through aligned filter elementopenings 404. The pin 401 may be machined, stamped, or moulded.

FIG. 63 shows a biodegradable pre-tapered pin 421 in a holder assembly420. The pin 421 extends through openings in filter element ends 423,and the pin has a barb 422 at each end, and the pin is bent throughapproximately 90° just before the barb 422.

Referring to FIGS. 64 to 67 a holder assembly 440 comprises a filterelement end 441 with a stop feature 442. A T-shaped biodegradablecoupler 443 has a head 444 through which the stop feature 442 extendsafter it has been twisted through about 90°. Then the filter element end441 relaxes, it is orientated so that the stop 442 engages behind thecoupler head 444. The remaining filter element ends are prevented frommoving by an elongate slot 445 in the stem of the coupler 443. FIGS. 68to 70 show variations as follows:

FIG. 68, a biodegradable coupler 450 has a slot 451 running its fulllength,

FIG. 69, a biodegradable coupler 460 is I-shaped, with two heads 462having openings 463, and a stem 461 with an elongate slot,

FIG. 70, a biodegradable coupler 470 is also I-shaped, having heads 472with a neck formed by protrusions 473 and a stem 471 with an elongateslot.

Referring to FIGS. 71 and 72, a holder assembly 480 comprises curvedfilter element ends 481, each having two ridges 482 at the end. Abiodegradable lure cap 483 has an internal thread 484, into which thecombined ends of the filter element 481 are engaged. This is shown inFIG. 72. The cap 483 may be fitted with a central lumen to aid flushingaway of acids formed through degradation.

Referring to FIGS. 73 and 74 a holder assembly 500 has filter elements501 with hooked ends 502 which snap fit into an opening in a dome-shapedbiodegradable cap 503. The cap 503 may be rigid or flexible. If aflexible cap is used, the filter element ends may make contact with eachother in the capturing position. When pushing together, the flexible capand filter element ends both deform until the filter element ends aresecured together in the capturing position.

Referring to FIG. 75 a holder assembly 520 comprises filter elements 521retained by a biodegradable C-shaped coupler 522 having a sleeve 523 ateach end push-fitted onto the filter element ends. The sleeve 523 hasproximal slots that the filter element snap features 524 fit into. Thedistal end of the sleeve is crimped or bonded onto a flexible or rigidbiodegradable coupler 522 that extends through openings in the filterelements.

Referring to FIGS. 76 and 77 a biodegradable tube 540 extends throughopenings in central filter elements 541 and top and bottom couplingfilter elements 530 are secured to the ends of the tube 540. Thecoupling filter elements are secured to the tube through crimping,bonding, or, interference fitting. The lumen allows washing away ofacids, produced during degradation, to slow down the degradationprocess.

Referring to FIG. 78 a holder assembly 560 has filter elements 561 withopenings 562 through which a biodegradable tube 563 extends. Stopfeatures secure the filter elements on the tube externally of theopenings. Again a lumen through the tube allows washing away of acidsproduced during degradation, thereby providing control over thedegradation period according to the selected tube configuration.

Referring to FIG. 79 a pin 585 is formed in situ in a series of openings581 in filter element ends. End filter elements have a recess 587 intowhich a cap, at the ends of the pin, is formed to retain the filterelements. The cap is formed through application of heat, ultrasonics, orsolvent moulding.

Referring to FIG. 80 a holder assembly comprises filter elements 600having two series' of ridges 602 separated by a gap 602. The filterelement is folded over at the gap 602 to engage with rings 603. The wallthickness of the gap section 602 is less than that of the filter elementto aid bending. Multiple ridges may be provided to facilitate use ofmultiple rings.

Possible materials for any of the biodegradable/bioabsorbable elementsdisclosed herein are listed below:

Polymers and composition percentages to achieve a 4-24 month filtrationperiod Polymer Composition (%) Poly(L-lactide)/Polyglycolide (PLL/PG)80/20 to 100/0 Poly(L-lactide)/Poly(D,L-lactide) (PLDL/PDL) 80/20 to98/2 Polyglycolide/Poly(ε-caprolactone) (PG/PCL) 10/90 to 40/60Poly(L-lactide)/Poly(ε-caprolactone) (PLL/PCL) 2/98 to 40/60Trimethylene carbonate (TMC) 100 TMC/PCL 60/40 to 95/5Poly(4-hydroxybutyrate) (P4HB) 100 P4HB/PLL 90/10 to 70/30 P4HB/PCL90/10 to 70/30

Using a biodegradable/bioabsorbable polymer, metal or ceramic materialmay allow for a wide range of filter conversion times.

With the vascular filter device of the invention the holding means maybe employed to temporarily hold the filter elements 6 in the capturingposition for any desired period of time. The invention is not limited toholding the filter elements in the capturing position for the periods oftime described above.

It is appreciated that the holder members may be manufactured ofbiodegradable material alone, a combination of biodegadable andbiostable materials, or, biostable materials alone.

The holder embodiments discussed above may be used to retain more thanone filter in the capturing state, for example a double cone filterprovided with a proximal fine cone and a distal coarse cone where thedistal cone converts at a time period after the proximal cone. Thiswould give extra protection in the initial stages of the treatment wherepulmonary reserve may be compromised temporarily.

An intervention may be performed to extend the protection period eithertemporarily or permanently. For example, a catheter would grasp a hookor feature near the holder and deliver a claw, c-tube, coil, or memorywire to prevent the filter elements from opening. The claw, C-tube, orcoil moves from an expanded state on the delivery catheter to a biasedcollapsed state where it retains the filter elements in the closedstate. In the case of the double convertible cone filter, it may bedesirable to extend the protection period only for the coarse distalfilter.

A double cone filter may be provided with a convertible cone and apermanent cone. Ideally, the proximal cone is convertible and has finercapture efficiency. This provides long term coarse filtration withinitial fine filtration.

It is appreciated that the filter embodiments discussed above can beused for general embolic protection in any blood vessel.

The invention is not limited to the embodiments hereinbefore described,with reference to the accompanying drawings, which may be varied inconstruction and detail.

The invention claimed is:
 1. A vascular filter device comprising: afilter comprising a plurality of filter elements, the filter elementsbeing movable from a capturing position to capture thrombus passingthrough a blood vessel to an open position to facilitate unrestrictedblood flow, and a holder to hold the filter elements in the capturingposition at a distal end of the filter elements, the filter elementsbeing biased towards the open position, the holder being configured totemporarily hold the filter elements in the capturing position untilelapse of a predetermined period of time, at least part of the holderextends through an opening in each of the plurality of filter elementsto hold the filter elements in the capturing position; and the pluralityof filter elements each include a twisted portion adjacent the holder,and an untwisted portion proximal the twisted portion the twistedportion being maintained in both the capturing position and the openposition.
 2. The vascular filter device of claim 1, wherein the holderis uninterrupted and has a consistent cross-sectional area throughout.3. A vascular filter device comprising: a filter comprising a pluralityof filter elements, the filter elements being movable from a capturingposition to capture thrombus passing through a blood vessel to an openposition to facilitate unrestricted blood flow, and a holder to hold thefilter elements in the capturing position, the filter elements beingbiased towards the open position, the holder being configured totemporarily hold filter elements in the capturing position until elapseof a predetermined period of time, at least part of the holder extendsthrough an opening in each of the plurality of filter elements to holdthe filter elements in the capturing position, and the holder includinga single biodegradable and/or bioabsorbable filament extending througheach of the openings in the filter elements to form a closed loop, witha first and second end of the single filament being tied together in asingle knot in a manner that secures the filament as the closed loopwithin the openings in the filter elements, wherein, the plurality offilter elements each include a twisted portion adjacent the holder, andan untwisted portion proximal the twisted portion.
 4. The vascularfilter device of claim 3, wherein the plurality of filter elementsinclude a twisted portion adjacent the holder, the twisted portion beingmaintained in both the capturing position and the open position.
 5. Thevascular filter device of claim 4, wherein the twisted portion of theplurality of filter elements is twisted through 90 degrees.
 6. Thevascular filter device of claim 3, wherein the plurality of filterelements include a wall located radially inwardly of the opening, thewall including a thickness that is greater than a thickness of a walllocated radially outwardly of the opening.
 7. The vascular filter deviceof claim 3, wherein each opening has a chamfered edge.
 8. The vascularfilter device of claim 3, wherein each opening in the plurality offilter elements faces circumferentially when the one or more filterelements are in the capturing position.
 9. The vascular filter device ofclaim 3, wherein the single filament is a first filament and the holdermember includes a second filament, the first and second filaments extendthrough the openings in the plurality of filter elements.
 10. Thevascular filter device of claim 9, wherein the second filament has firstand second ends, wherein the first and second ends of the first filamentare tied in the knot with the first and second ends of the secondfilament.
 11. The vascular filter device of claim 10, wherein the firstand second filaments extend twice through only one of the openings ofone of the plurality of filter elements, and the knot secures the twofilaments directly to said one of the plurality of filter elements. 12.The vascular filter device of claim 3, wherein the single filamentextends twice through one of the openings of one of the plurality offilter elements, and the knot secures the single filament directly tosaid one of the plurality of filter elements.
 13. The vascular filterdevice of claim 3, wherein the opening is formed by a hook-shaped end ofeach of the plurality of filter elements.
 14. The vascular filter deviceof claim 3, wherein the knot additionally secures the single filamentdirectly to one of the filter elements to form an anchor point for theknot.
 15. A vascular filter device comprising: a filter comprising aplurality of filter elements, the plurality of filter elements beingmovable from a capturing position to capture thrombus passing through ablood vessel to an open position to facilitate unrestricted blood flow,and a biodegradable and/or bioabsorbable holder to hold the one or morefilter elements in the capturing position, the plurality of filterelements being biased towards the open position, the holder beingconfigured to temporarily hold the plurality of filter elements in thecapturing position until elapse of a predetermined period of time,wherein at least part of the holder extends through an opening in eachof the plurality of filter elements to hold the plurality of filterelements in the capturing position, the holder including a singlefilament extending through each of the openings in the filter elementsto form a closed loop; the plurality of filter elements each include atwisted portion adjacent the holder, and an untwisted portion proximalthe twisted portion; and the single filament includes first and secondends, wherein the first and second ends of the at least one filament aretied in a single knot to secure the closed loop, and the at least onefilament extends twice through one of the openings of one of theplurality of filter elements and extends only once through each of theopenings of the other filter elements, and the knot secures the at leastone filament to the plurality of filter elements, and additionallysecures the filament directly to said one of the plurality of filterelements.